Pulse duration discriminator



y 1951 L. H. ORPIN PULSE DURATION DISCRIMINATOR 5 Sheets-Sheet 3 Filed April 22, 1947 3nventor M y 1951 L. H. ORPIN 2,552,013

PULSE DURATION DISCRIMINATOR Filed April 22, 1947 5 Sheets-Sheet 4 To Previous Amplifier From Next MVBR a6 Iftfnenjor Gttorneg Patented May 8 1 951 T UNITED -PULVSE. DURATION mscmnmeron Lionel H.'0rpin,.Greece, N. 1Y., assignor. to..G.eneral RailwaygSignal Company, Rochesten N Y.

A pl at q pri fiz 1947, fi a N 33 11 L18. Claims. (Cl..177.353)

"This invention relates to -pulse duration-discriminators and more particularly to electronic discriminators capable of accepting or rejecting, that is repeating or not repeating electrical pulses dependent on their length-or'duration.

In the prior applicationof Kendall and Orpin, SerJNo. 672,750; filed May-28,--l946, nowabandoned, discriminators capable of performing similar functions have been -disclosed and it is contemplated that the discriminator -of' -the present invention willbe used in similar systems but has application in many other-forms of pu1se technique electronic systems. Because-Mae apparatus of the present" invention is capable of determining the particular circuit over which an electrical pulse shall flow, depending -upon its length, the system of the present invention may also be considered to be a switching system.

One of the objects and purposes of --the present invention resides inthe construction-ofadiscriniinator which is very critical mits-ability to interpretthe duration of a pulse, or if desire'd the amplitude of a pulse.

Another object of the present invention 7 resides in the construction of a discriminator which is very critical inits ability to interpret the duration of a pulse, or ifdesiied the amplitude of; a

pulse, and to direct such a pulse to a particular 'circuit in a network.

Another object of the present invention resides 30 in the provision of apparatus which is capable ,pulse of commensurate amplitude orheight. Thereafterthe converted pulse maybe conducted to an amplitude discriminator comprising; one or more critically adjusted amplifiers or oneor more ,multivibrators, each of which will respond only if the pulse applied thereto is of predetermined .or greater amplitude and each successive one adjusted to respond only to pulses of successively greater amplitude. In the case of the multivibrators, these are utilized in cooperating pairs to control an output-circuit, with *the 'm'ultivb" 2 flip-flop action.

brator which-is adj-uste'd to respond to pulsesnf lesser amplitudebeing adapted to produceanoutputfrom the output circuit-and the othenmifltivibrator,- which isadjusted ---to respond tohpulses of the greatermagnitude,being utilized to disable such output circuit orprevent' it from functioning if-apulse of such-greater magnitudeis .Z'received. 1 In the-case ofthe critically adjusted amplifiers,.-it is-further-proposed to have each ofthese amplifiers-'adapted to control. a-multi'vi- 'brator which will produce an output-pulse of substantially fixed amplitude .4 and duration, to provide a gated-amplifier or-double inputlcontrolled amplifier -for "each i such multivibrator,

except the last enact -the series,.and to allow each such-amplifier tot-respond. 'only. if. -.the.; -first of its-two associated...multivibratoi's.performsa cycle ofl-o peration and. theother- .multivibrator does notperform such a cycle .of..operation,, .,,or In other words, .-this .I.latter amplifier functions only ifthepulseis of a; durationgreat enough to result-in the.- operation..oi one multivibrator ..but is ..not. sufiiciently .long. .to cause operation =ofwthecnext. critically adjusted 2 amplifieigfcapable..of tresponding toa slightly longer. .pulse andits associatedlmultivibrator.'

As another lobjectiof. .the. present; invention. it is. proposed ,to use a.,.=c-d0ub1e .input controlled .amplifieror agated amplifier v.to supply ancinput to a. gas-type vtuberwl'iicht in turn controls. some suitable electric-responsive device. such -as... a relay.

- A lurther objectof the-.presentinvention is to .provide means furnishing. a..constant.. power ..out-

p nt .tooperate an. electro=-responsive device from an. input .of constantly vrepeated..pulses. whose repetition .frequencyi mayavary between wide tlimits.

- Other objects purposes-and characteristic fea- 40 "tures of the: presentoinvention, .will .in. part1.be

--more= fully pointed out. hereinafter and Will-.in .partbe obvious from the accompanying. drawings in-which Fig. 'lshows incircuit diagram form one ele- 5 -ment of-this invention;

=Fig. 2 shows in block diagram-form-an embodi- -ment of this invention;

--Ffig. 3 is a circuit-diagram ofthe embodiment shown im-bloekdiagram.form in Fig; 2; F r Fig. 4: shows another embodimentofathe pres ent invention in-circuit diagramform;

-Fig.-- Ai -shows a modified element which amay be substituted. for an-=element -of-the Fig. 4' -cir- --cuit;

-Fig.- ib shows a modifiedelement which may be atta'pi 3 Substituted for another element of the Fig. 4 circuit; and

Fig. 5 illustrates an operational time chart of a system such as shown in Fig. 4 but expanded to include at least four relays capable of being independently controlled by the discriminator.

In Fig. 1 is shown one element of this invention which is responsive only to input pulses Whose durations are equal to or greater than a predetermined value. Negative input pulses are coupled through coupling condenser l5 to the control grid of electron tube It. In this application the first grid in an electron tube starting at the cathode is called the control grid; the second grid, the screen grid; and the third grid, the suppressor grid; the latter being utilized to suppress secondary emission from the plate of the tube. The plate of this tube is connected to ground through condensers l1 and I8 in series and to a positive source of potential through plate resistor I9 and resistor 20 in series. The junction point of condensers I1 and I8 is connected to the grid of electron tube 2! and through resistor 22 to arm 23 of potentiometer 24, whose end terminals are respectively connected to a negative source of potential and ground. The plate of tube 2| is connected through coupling condenser 25 to the the grid of electron tube 26, the output of this latter tube being taken from its plate via coupling condenser 21. The control grid of tube I6 is also connected to ground through the parallel combination of rectifier or diode 28 and resistor 29. The other circuit connections are conventional as shown.

Operation.-Tube it normally is on or conducting due to its grid and cathode being connected to ground, and each negative input pulse applied to its grid through coupling condenser [5 will turn the tube off, allowing the condenser IB to start charging up toward the potential of the positive potential source. By making the capacity of condenser l8 small in relation to that of condenser H, the time constant of its charging is controlled mainly by the resistance of resistor l9 and the value of its own capacitance. When the negative input to the grid of tube It ceases, the tube again conduets, with the result that a saw-tooth wave is produced at the junctions of condensers l1 and 18 whose peak amplitude is a measure of the length of time that the grid of tube It was negative, or in other words, a measure of the duration of the negative input pulse applied to the grid if the duration of the applied pulse is less than the time constant of resistor l9 and condenser I8. By adjustment of arm 23 of potentiometer 24, amplifier tube 21 can be biased so that it will conduct only for an input saw-tooth whose peak amplitude exceeds a predetermined value. For example, this adjustment can be made such that tube 2| will be turned on only for a saw-tooth whose amplitude corresponds to an input pulse applied to the grid of tube [6 of one microsecond duration or greater. The tube 21 thus provides at its plate a negative output pulse whenever a negative input pulse of desired duration or greater is applied to the grid of tube 6. The purpose of diode 28 is to prevent grid current from flowing in tube l6 and also to prevent positive or negative overshoots when the negative impulse is removed. If a positive output pulse is necessary, this negative output pulse may then be coupled via coupling condenser 25 to amplifier-inverter tube 26 and 4 the output taken from the plate of tube 26 via coupling condenser 21. It will be obvious, however, that tube 26 and its associated circuitry are not essential to the invention.

In Fig. 2 is shown an embodiment of this invention in block diagram form, this embodiment requiring that an input pulse be of less than one predetermined durationas well as greater than another predetermined lesser duration for its operation. The output of an integrator 30 is connected to the input of a phase inverter 3|. The two outputs of phase inverter 3| are connected respectively to two multivibrators 32 and 33, the output of multivibrator 32 being connected to one input of output circuit 33 and the output of multivibrator 33 being connected through an associated differentiating circuit 35 before being connected to a second input of output circuit 34. As illustrated by the wave forms in Fig. 2, a negative input pulse of width indicated by the dotted lines is transformed by integrator 30 into a positive saw-eooth pulse or signal of constant slope and the same width as the input pulse. The resultant positive sawtooth output of phase inverter 3| is utilized to trigger multivibrator 33 into operation, and the negative voltage gate obtained therefrom is "differentiated by differentiating circuit 35, re-

sulting in a negative spike coincident with the leading edge of the negative voltage gate and a positive spike coincident with its trailing edge. This positive spike will be utilized to trigger output circuit 34 into operation to produce a resultant negative output pulse providing output circuit 34 is not subjected to a blanking or disabling pulse or gate from multivibrator 32. Multivibrator 32 is triggered into operation by the corresponding negative saw-tooth from phase inverter 31 if this negative saw-tooth is of suflicient magnitude. If triggered into operation multivibrator 32 will provide a negative voltage gate output which when applied to out- 'In Fig. 2 no such voltage gate output is shown spike received from differentiating circuit 35.

from multivibrator 32 since it is assumed that the input pulse to integrator 30 is not greater than the desired pulse width. Thus, by proper adjustment of multivibrator 33, an output will be produced from output circuit 34 only if the input pulse to the circuit is equal to or greater than (as shown) one desired pulse width, and by proper adjustment of multivibrator 32, output circuit 34 will be disabled from producing an output if the input pulse is of greater width than a second fixed pulse width limit greater than the first above-mentioned. As indicated by the wave forms, the negative output of multivibrator 33 must start at least a short time before the trailing edge of its input saw-tooth wave, and the trailing edge of the negative gate output may occur any fixed time desired thereafter, preferably being of the order of a few microseconds, however, in order not to cause too great a delay between the leading edges of the input pulse to integrator 30 and the output pulse from output circuit 34.

In Fig. 3 is shown a complete circuit diagram of the embodiment illustrated in block diagram form in Fig. 2. The negative input pulse is coupled by coupling condenser 40 to the control grid of integrator pentode 4|, whose screen grid is returned to a positive source of potential through resistor 42 and whose suppressor grid and cathittfdrt;

. 5 l th trench-necte together and to ground. The plate oftube 4i "is'f'conne'cted to the samesource of positive potential through resistor '43 and to ground "through condensers 4'4 and 45 'inseries, and its control grid is returned to ground through esistor 46. "The junction point of condensers and 45 is cbnnected'to 'grou rrdthrough resistor 41 and to the control grid'ofphase inverterpentode 43, whose screen" grid is'c'onnected to the A above menti'oned source of positive potential through resistor 49 andwh'os'e suppr'es'sorig'rid andcathode "are connected "together and to ground through the resistance strip of potentiomet'er 59. The plateof peritode'4Bf is connected to the above-mentionedsourc' 'of positive potential through the resist'ahcej'strip of potentiometer 51. The slider arm 52 Of potentiomete 513 'is connected through coupling condenser" 53 to the grid of tube 54, and'slider arm 55 o potentioineter 5i iscconnectedlthrough coupling condenser 58 to the grid 'oftubetl The plate of tube '54 is connected to the'same source of positive potential through resistor 5B,to the" grid of'tube 59 through condenser 86, and to the control grid of pentode 6| through differentiating condenser 62, and "its control grid 'is returned to ground through resistor63. The plateof tube 59 'is connected to the above-mentioned source of positive potential through resistor 64 and to the grid of 'tubej'54 through coupling condenser 65, its grid is returned tothe same source of positive potential through resistortfi, and its cathode and'that of tube'54 are connected together and to ground through resistor 61. Thus, tubes 54and 59 constitute adelay multivibrator 33. The plate of tube51 is connected to the above-mentioned source of positive potential through resistor 68fand to the grid of tube 69 through condenser Iii, its grid is 'returned to the same sourceof positive potential through resistor H, and its cathode 'and' that of tube 69 are connected together and to'ground through cathode resi'stor'l2. The plate'of tube 69 "i connected to the same source of positive potential through resistor 13 and tothe screen grid of pentode 6! through condenser '74, andiits grid is connected to ground through resistor 75. Thus, tubes 5! and 69 constitute the second multivibrator 32. The screen grid of pentode 'BI is also tied to the junction point of resistors '16 and Ti, which are connected in series -l'le'tv've'en the above-mentioned source of positive "potential and ground, thus positivelybia's'ing this screen g rid. Thecontrol grid of pent'ode' Slis returned to ground through differentiating resistor '38, its suppressor grid and cathode are connected togetherand to the saihesour ce of positive potential through resistance andfto ground through resistor" 80 and c'ondenser"8l connected in parallel, and its 'plateis connected I;

6 iiurationof the input pulse to "tube *4 I A n of the 'positive js'aw-toothfiat thecatho de :48 is picked "off by arm 52 of potentiometerfig and co'n'nected'to the delay-multi- 'vib ator 33 "comprising tubes 54 and-59, and "'a portion" of the corresponding' negative saw-tooth appearing "at-the'plate of tube ES-is pickedoff by arm 55 of potentiometer-5| and connected to the 'niultivibrator -3'2- comprising tubes 5'! and s5, 11 the*i'np'utpulse applied to tube 41 is er suiiicier t "duration, the portion of the positive s'aw tooth thus applied to the grid ;of tube 54 Willturn this tube on and'tube 59 abruptly "fofififand this condition will obtain for a "time i liredljy the circuit constants of 'multivibrator 33, preferablyassumed to be on the order ot a 'fewjnficroseconds as 'above explained. Theresu lti'ng neg'ativ'e pulseor voltage gate at the plate of tube' 54is differentiated by-differentiatingcircuit 35; comprising condenser 62 and resistor 3 l8, and the positive differentiated pulse produced coincident with-the trailing'edge of thi negative'voltag'e gate is applied to the control grid of output pe'ntode 6! to produce'an output at the plate ofthis tube if-a negative voltage' 'gate isfnot'"simultaneouslyapplied to its screengrid. The-portion of the negative saw-tooth applied to the grid of tube'iil if of sufiicient magnitude, will turn this tube offf 'andtubetQ on abruptly, producing a negativevoltage gate at the pla'te'fof tube-'59, and thiscondition will continue jforaftime fixed by the circuit constants of this "inultivibrator '32. Adjustment of arm 52 of potentiometer ie controls the minimum input pulse 'd uration which will trigger the multivibrator' gamma-18mg tubes'54" and'59, into operation to produce an output from'pe'ntode 6!, ahdadjustment of-arm- 55 'of potentiometer 5| controlsthe maximu'm duration pulse passed-by thepentode 6!, since if a pulse' greater than this maximum setting is received, it willtrigger mu1- 'tivibrator 32, comprising tubes 5'! and 69, into operation, thus producing a disabling negative yoltag'e gate at the plate of multivibrator tube 'EQwhich'Willthen be coupled to the screen grid normally off or noii conducti'ng due'toits cath- 4 'th'is saw-tooth"attainsbeing adirett measure 3 'l'o ff'fp'ento'defEH to' prevent its operation even though a difi erentiated positive pulse from condenser 62 'is"simu1taneously received at its control grid.

In Fig. 4'are shown typical circuits of another embodiment which is adapted to identify and separate pulses of various durations, pulses of each distinctive duration being utilized to opera'te' a typical control circuit such as that shown.

- By referringto Fig. 4 it is readily observed that "the'fnrst'two tubes SI and 92 are common to-a plurality of chains or series of tubes each terminating ina relay, Of'WhlCh the first chain has been shown completely and "the second chain fragmentarily. Thefirst tube 9| is an integrating tube which hasthe values of its plate condenser 93 and plate'resistor 94 so chosen that the output of the'plate circuit will gradually increase'inamplitude during the time an input pulse of sufficient' magnitude to drive tube 9! below cut-off isapplied to'its control grid, so that the "amplitude of the ultimate plate output potential depends upon the duration of the pulse. That is, tube" 9! converts a pulse'of any particular duration into a saw-tooth pulse of commensurate amplitude, As is' readily seen, the output from tube 92 is-takenfrom its cathode "circuit and-{constitutes the voltage drop across resistor- 95. Tubef92 is'thus' a cathode follower which-uses not materially change the shape or the saw-tooth pulse nor its amplitude, but does enable appreciable current to be drawn from its cathode circuit without appreciable attenuation by reason of the low impedance of this output cathode circuit. The output from tube 92* is applied to the control grids of a plurality of critically adjusted amplifiers 96, 91, etc., via couplin condensers 98, 99, etc.

Tube 95 has its control grid biased below cutoff, the amount of this bias being controlled by the setting of potentiometer I since this grid bias is obtained to a large extent through the medium of the screen current flowing through screen resistor IIlI, cathode resistor I02, and the effective portion of potentiometer I00 in series. By referring to Fig. it will be seen it has been assumed that potentiometer. I00 has been adjusted such that the critically adjusted amplifier 96 connected to multivibrator I03 will not respond to a pulse corresponding to an input pulse of 0.6 s. (microseconds) duration, but will respond to a pulse corresponding to an input pulse of 0.7 1.8. duration or any pulse in excess thereof. It will also be seen that the next amplifier tube 91, which precedes the multivibrator I04, will respond to pulses of 1.5 ,uS. for longer duration. Similarly, the next two chain critically adjusted amplifier tubes (not shown) will respond to pulses corresponding to 2.5 to 3.5 microsecond input pulses respectively.

The ohmic value of resistor I02 in the cathode circuit of tube 96 is so chosen with respect to the other circuit parameters that this tube has a degenerative feed-back effect. Thus if pulses of substantially greater amplitude than that necessary to cause the tube to conduct are applied to its control grid, the amplification of this tube will be reduced and the amplitude of the pulse from its plate circuit will hence be reduced from what would otherwise be expected. Furthermore, this degenerative feed-back eiTect will produce a pulse in the plate circuit of comparatively short duration. The reason for this designed iunctional characteristic of amplifier tubes 96, 91, etc., is that it is desired to have these tubes initiate their respective associated multivibratorsl03, I04, etc., only once for each pulse produced in their respective plate circuits.

As shown, the plate output from tube 96 is coupled via condenser I05 to the control grid of the right-hand or on tube of the multivibrator I03, which is a so--called one-shot multivibrator with positive grid return. This output pulse from tube 96 is negative, and its application to the grid of the right-hand or on tube will cause a reduction in the current flowing through this tube. This reduction in current flow in the right-hand tube plate circuit will cause its plate potential to rise abruptly and thereby transmit a pulse of positive polarity through condenser I06 to the control grid of the left-hand tube of multivibrator I03. In other words, the conduction of the right-hand tube decreases and the flow of current through the left-hand tube increases, and this continues until temporary stability is reached with conduction of the lefthand tube at a maximum and that of the righthand tube reduced to zero. During this temporary stable condition, current flow through resistor I01 charges up condenser I05 and raises the potential of the grid of the right-hand tube gradually until it reaches cut-oil. At the same time condenser I06 is being gradually discharged due to current fiow through resistor I08. When the potential of the grid of the right-hand tube reaches cut-oif, this tube again conducts, its plate potential is thus reduced suddenly, and this reduction in potential is coupled back via condenser I06 to the grid of the left-hand tube, turning this tube off. This is the normal stable condition of multivibrator I03, with its righthand tube conducting and its left-hand tube substantially non-conducting.

This cyclic action of multivibrator I03 thus produces a momentary negative voltage gate in the plate circuit of the left-hand tube as is shown in the wave forms for multivibrator I03 (Fig. 5, line C). This negative gate is next coupled to the control grid of amplifier tube III through a differentiating network including condenser I09 of extremely low capacity, for instance, 40 micromicrofarads, and resistor H0, having an ohmic value of say 12,000 ohms. This differentiating network causes the beginning of the gate applied thereto to produce a sharp negative potential drop or spike across resistor H0 and the end of this gate to produce a positive spike of lesser amplitude and duration but still of sufiicient amplitude to bring the grid voltage of tube III above cut-off to render this tube conducting unless its control grid is simultaneously made negative by a gate delivered from the multivibrator I09 of the next series or chain through resistor H2 and its associated condenser H3 in series. The negative and positive spikes have been shown in the graph representing the waveform at the grid of tube I I I, line D of Fig. 5 of the drawings. The negative spike delivered from the plate of the left-hand tube of multivibrator I03 to the grid of tube III will, of course, have no effect because this tube is biased to cut-off, this negative pulse thus merely increasing the negative bias on the tube. The positive spike, however, which is also created by the differentiating network, is of sufilcient magnitude and of the proper polarity to overcome this negative grid bias on tube III as shown and thereby causes tube III to be turned on or conduct.

This conduction of tube III produces a negative pulse of short duration on its plate circuit (line E, Fig. 5) which is coupled through the diode I I4 (Fig. 4) to the control grid of a normally conducting D. C. amplifier I I5. The plate circuit of amplifier H9 is coupled to the control grid of a gas-type tube II 0 through resistor III. In practice it is assumed that the pulses to be discriminated by the apparatus of the present invention are repeated periodically at any desired rate, such as 15 times per second, and these repeated negative pulses flowing through diode II I will produce an accumulation of negative charge on the grid of D. C. amplifier H5 sufiicient to reduce the conduction of this tube and thereby bring its plate potential up to a value where the ensuing tube H6 will fire or conduct. Tube H6 has its cathode normally biased positively to such an extent that the tube Will not fire in response to the A. C. Voltage applied to its plate circuit. This cathode bias of tube II 6 is produced due to its cathode being directly connected to the cathode of amplifier H5, there being a normal fiow of cathode current through this amplifier H5 and also through resistor H8 to ground due to amplifier I I5 being on or conducting. In other words, the cathode current of tube H5 flowing through resistor H8 maintains the potential of the cathode of gas-type tube I I 6 above its grid potential so that its grid is therefore negative with respect to its cathode. It will be seen that this potential at the grid of tube angel-.8:

one of which includes resistors, Ill and I and,

the other the internal resistance oitube I I5 It is thus seen that when the, conduction through tube I I5 decreases, as. it will. in response to the application of a negative potential to its control grid, not only is the potentialat the plate, of tube I I 5 increased to thereby'increase the gridpotem tial on tube lI6-,but. also theresistance drop through resistor, I IBfis decreased. to thereby reduce the potential at. the cathode of tube II 6,

and this double'or accumulative efiect upon the potential difference between the grid and oath: ode of tube II6 will causethistube to fire during every positive cycle, of A. C." current, flowing from the secondary coil of; transformer I2! through the relay I22, both of which are in the plate circuit of tube I IB'as shown. Obviously, if

negative pulses flowing, through diode I- I4, cease,

the negative pulses applied to the gr id of tube II5 will disappear and this tubefwill again conits plate circuit. "That is, the relay I22 will be deprived. of energy at the end or the first'poslitive wave of alternating current applied to the plate circuit of. tube Ilfifollowing the fall in potential. of itsgrid below that value at which the tube will fire. The contacts of relay I122 will ct course thus open when pulses are no longer delivered from the plate circuit of the double input control amplifier III. 'r V r It should now particularly be noted that if the pulse under consideration should be of such duration that both of the amplifiers 95 and 9! are caused to conduct and both of the associated multivibrators I03 and I04 are caused to operate through one cycle of operation simultaneously, the gate produced by the multivibrator I04 will completely neutralize or overcome the positive spike created by the difierentiating, network preceding tube I II. As a result, the double inpjut controlled amplifier I I I. will not be caused to conduct and hence the relay I22 will not operate. In other words, in order to pick up relay I22, the pulse must be of suificient duration to actuate amplifier 96 but must not be of sufficient duration to actuate amplifier 91.

In this connection it should be observed that the negative voltage gate or pulse that is produced at the plate of the left-hand tube of multivibrator I03 and applied to the grid of tube I Il may also after several difierentiations reach the grid of tube I23. Before this pulse, however, reaches the grid of tube I 23 itmust pass through resistor II 2 'and three differentiating" networks I09--IIO, II3-I24, and 125-426. Because of these three networks, the resultant input at the grid of tube I23 due to this negative'pulse is appreciably reduced in'magni'tude'and it is" also attenuated by its passage through'resistor H2. In other words, bythe time the resultant signal reaches the grid of tube' I23, it is nolonger of sufiicient amplitude to cause this" tube to conduct. Therefore, even though this structure constitutes a maginal arrangement, it is in fact reliable because the margins of operation are sufiiciently great. Furthermore, the amplitudeof thevoltage gates delivered by he multivibratoijs I03, lMfetcL, are fixedby 'des n andare iridependent of the amplitude ofv the original pulse received at the grid of tube 9|.

As above-explained, the second chain has been shown only fragmentarily, including amplifiers 97 and I 23 and multivibrator I04. The circuit.

components, connections, and operation of these are similar to those of amplifiers 96 and III and multivibrator I03, respectively, and hence will not be discussed here in detail. The output of amplifier I23, taken from its plate, is fed to an output circuit not shown butsimilar to that illustrated for the first chain, including diode I, D. C. amplifier H5, and gas-type tube H6, and controlling a relay I22. The output from a third chain multivibrator (not shown). is also coupled through a condenser I2] and resistor I28 in series to the control grid of double-input, con trolled amplifier I23 for disabling purposes as will be pointed out more specifically hereinafter in connetcion'with Fig. As previously indicated, double-input con trolled amplifiers II I, I23, etc., may be replaced by gated amplifiers, which perform the-same function,'and in Fig. 4a has been illustrated such a gated amplifier [23a and its associated circuit, which 'may be substituted 'for the doublein'put controlled amplifier I23 of. Fig. 4 and its asso-' ciated circuit. Although the margins of opera tion of double-input amplifier I,23'are more than adequate and therefore safe, as above-discussed," ifv it is replaced by the gated amplifier 123a, of Fig. 4a, all questions of margins will be removed inthatj two independentg'rids on the same tube are controlled. and no circuit connections of, kind exist between the control grids of the'various gated amplifiers. H H The operation of the system is substantially the same irrespective or whether the double input controlled amplifier I23'or the gated'ainplifier [23a of Fig. 4a is employed. 'If amplifier I23fis used, the suppression or disabling'function is accomplished by the transmission of a negative gate'to its control gridywh'ereas if the gated amplifier I 23a is used, such anegative gate is transmitted to its screen grid to suppress or dis able the tube action in spite of the simultaneous transmission of a positive pulse to its control grid; Referring to Fig. 4a it will be observed that an,

of, the resistors associated with tube I23a are the same as those associated withtube' I23 except that resistor I29, and condenser I30 have been omitted and that resistor I3,I has been added. Resistor I3I has been added to provide a definite and fixed positive bias on the screen grid so that this tube will conduct if a positive pulse of'adequate amplitude is applied to its control grid but will not conduct if simultaneously therewith a negative pulse is applied to the screengrid via a diode or rectifier I32. The conventional show-f ing of rectifier I32 includes a downwardly point ing arrow, signifying that positive pulses will'be conducted in'a downward direction and negative pulses will be conducted in an upward directioi f The operation of the system is substantially the same when the gated'am'plifier'l23a is used as when the double input controlled amplifier" I23 is used, for which reason the'operation of the system 'whenmodified as illustrated in Fig' i'd will not be further discussed in detail. In Fig. lbis shown a modified circuit which may be substituted for the relay control circuit comprising tubes H4, H5 and H6 and transform'er I2I of Fig. 4. Briefly, it includes a rnul i"' vibrator I35, power arririlifier'ISB, and ree '31- hi 'mqd d r it ro des e teni a e EL 1 power to relay 22 from the source of regularly repeated pulses available at the plate of tube III (Fig. 4) and provides foolproof and dependable operation of relay I22 in that the relay will not be operated by ordinary failure or disarrangement of the circuit components, thus insuring that when relay I22 operates it is because a pulse input has been applied to multivibrator I35. As indicated, the output from the plate of tube II I (Fig. 4) is applied through coupling condenser I38 to the grid of the first tube of one-shot multivibrator I35, and the output from the plate of that same tube is coupled through condenser I39 to the grid of biased inverter-amplifier I35 which is designed to be of the power amplifier type. The output from the plate of tube I36 is coupled through condenser I40 and rectifier H31, which preferably is of the bridge rectifier type in order to obtain the largest possible power output, to the coil of relay I22. This circuit of Fig. 4b, as above-mentioned, will deliver a constant power output in response to an input of regularly spaced pulses whose repetition frequency may vary within wide limits, these limits of the circuit shown being 7 to approximately 10,000 C. P. S. Multivibrator I35 produces a variable frequency output of approximately equal positive and negative halves, this variable frequency being dependent, of course, upon the repetition frequency of the input pulses, and this multivibrator will.

frequency divide up to the limit of its given circuit parameters if its free-running designed frequency is greater than fifty per cent of the input pulse frequency. Initially the multivibrator constants are chosen to obtain a square Wave output for the lowest input pulse frequency desired (in this case, '7 C. P. S.) and therefore a square wave output will be obtained for any greater frequency up to the limit fixed by the circuit parameters chosen (approximately 10,000 cycles here). Inverter-amplifier I36 is normally off due to the negative bias provided as shown, and the output of multivibrator I35 being applied to its grid results in a greater amplified square wave being produced at its plate, this amplified square Wave thereafter being full-wave rectified by rectifier I31 in order to supply rectified D. C. to operate relay I22. Providing condenser I40 is large enough (approximately 2 microfarads in the embodiment shown), except for multivibrator I35 the circuit illustrated is frequency insensitive above the lowest frequency for that which it is designed, e. g., '7 cycles, or in other words, the power output to the relay is constant above that frequency. It is, of course, obvious that bridge rectifier I31 shown could be replaced by any other rectifier circuit, one-half wave or fullwave according to the particular power output requirements, and that the output of the circuit of Fig. 412 instead of being applied to the coil of relay I22 could be used for many other purposes. For instance, by applying the output through a condenser for smoothing purposes, a D. C. bias voltage would be produced which could be used for a multiplicity of biasing applications.

Operation.Let us now assume that the apparatus illustrated in Fig. 4 has been expanded to include five previously adjusted amplifiers, five cooperating multivibrators, four double input control amplifiers (Fig. 4) or gated amplifiers (Fig. 4a), four relays, and four associated cooperating relay control circuits according to Figs. 4 or 41). As is readily understood from Fig. 5 and as will be more fully pointed out hereinafter, the four successive amplifiers (the first two of which comprising tubes 96 and 91 respectively, are shown in Fig. 4) will respond to pulses whose durations lie within the limits 0.7 and 1.5, 1.5 and 2.5, 2.5 and 3.5, and 3.5 and 4.5 microseconds respectively. Thus it is seen that there are five series or chains of tubes such as 96 and I03 and that there are only four series of tubes such as III, H4, H5, and H6; IIIa, H4, H5, and H6; III, I35, I36, and I31; or IIIa, I35, I36, and I3]. It should thus be apparent that each double input controlled or gated amplifier is controlled by two multivibrators if it is desired to fix both an upper and lower limit to the duration of the input pulse to which each responds, and this is the reason for requiring, by one, more multivibrators than double input controlled or gated amplifiers. Of course, the additional multivibrator might be dispensed with if it was desirable that, or immaterial whether, the last successive relay operated in response to an input pulse of greater than the predetermined magnitude. Thus in the present embodiment, the elimination of the fifth multivibrator would cause the fourth or last amplifier and relay to operate in response to any input pulse Whose duration exceeded 3.5 microseconds. Also, while in the present embodiment each double input controlled or gated amplifier has been described and shown as being controlled by two adjacent multivibrators, it is of course obvious that this is not necessary. As an example, the circuits shown could be modified to have the operation of the first amplifier, for instance, disabled by the fourth, or third and fourth, or second and third multivibrators if such was desirable in a particular application.

In Fig. 5 the functions performed by the group of devices assumed for the present embodiment has been graphically illustrated. The first line, line A illustrates pulses of the various widths or lengths. Line B shows the resultant saw-tooth outputs produced at the output of the integrating tube BI when the five different pulse lengths illustrated in line A are applied to its control. grid in succession. It will be seen that the first pulse, which is assumed to be of 0.6 s. (microsecond) duration, will produce a saw-tooth pulse of insufiicient amplitude to cause any one of the tubes 96, 91, etc., to conduct. The second pulse, assumed to be of 1 s. duration, creates a sawtooth pulse of amplitude suificient to cause amplifier 98 to conduct and the multivibrator I03 to perform a single cycle of operation, but not sufficient to cause tube 91 to conduct. This will cause amplifier II I to conduct because no blocking or disabling pulse has been received via resistor IIZ. Fig. 5 does not show performance beyond the amplifiers III, II2, etc., but the functioning of their respective relays I22, etc., is, of course, controlled by these amplifiers as above-described. It will be recalled that none of the relays I22, etc., are energized in response to pulses of 0.6 s. duration, that relay I22 only is energized if the pulse is of l ,uS. duration, that the next relay only is energized when the pulse is of 2 ,uS. duration, that the next successive relay only is energized when the pulse is of 3 ,uS. duration, and that the last relay only is energized when the pulse is of 4 s. duration. As shown by the dotted saw-teeth (line B, Fig. 5) and the dotted pulses (line A, Fig. 5) about one-half microsecond variation in pulse length both above and below these values may be tolerated without a change in results.

Referring again to the portion of Fig. 5 directly below the 1' microsecondpulse-illustrated;

itwill be seen that the multivibratorlm' creates a voltage gate output (line-C), and that the on' the grid of this tube-was not neutralizedrby a gate delivered from themultivibr-ator I04:

through the circuit including condenser l l.3 and resistor ll2' (line E).

Referring now to that portion of Fig: 5: applying to a 2 s. pulse, it will be seen that nega-- tive' gates are produced by both multivibrat'ors lfl3 and Hi4 (lines C andF, respectively) andthat thelater gate (line F), produced by multivibrator I04; has been impressed upon the grid of tube I II via resistor H2: and condenser Ht? so that this grid is not brought above cut-off by the pulse from its own multivibrator. H33;

(-line D), and thus tube 1- will not conduct (line E). As can been seen in line 13, this isbecause the voltage gate produced by multivibrator [M pulls the grid voltage of tube HI down below cut-off at that point where thesec- 0nd and positive spike exists so that this spike Be cause tube l H does not" conduct, the pulse which would otherwise have been produced at its plate can no longer cause tube Hi to conduct.

circuit has been indicated by dotted lines in line E, meaning that such pulse does not now exist. In other words, even though the-2 microsecond pulse will cause operation. of bothtube 96 and multivibrator I 0-3, tube III will notconduct current and the relay 122' controlledthereby will not operate. The next chain re.- lay will, however, operate due to amplifier I23 conducting (line H). Similarly, for a 3. #5. pulse the next multivibrator will render inefiective the pulse applied via tube 91 and multivibrato-r IM to the control grid of tube I23: (line G) because this control grid is brought negative by a gate produced by this next multivibrator (not shown in Fig. 4), this gate being conventionally illustrated for the 3 s. pulse in line I. The operation of the circuits for a 3 s. pulse is illustrated in lines I, J, and K and for a 4 s. pulse in lines L, M, and N in a similar fashion and will not be discussed in detail. It should be noted, however, that line 0 represents the output of the fifth multivibrator, which as above-men tioned has no associated cooperating fifth amplifier similar to amplifier 123 or |23a and whose only function is to disable the fourth amplifier if the duration of the input pulse exceeds 4.5 microseconds. The operation of the fifth multivibrator in that event has been indicated by dotted lines in line 0, and its consequent effect upon the fourth amplifier by dotted lines in lines M and N, this effect being similar to that above-discussed in connection with the other amplifiers HI, I23, etc.

Attention is again particularly directed to the fact brought out by the operational time chart of Fig. 5 that for a 0.6 microsecond pulse none of the relays are energized, for a 1 microsecond pulse only the relay I22 is energized, for a 2 microsecond pulse only the next relay is energized, for a 3 microsecond pulse only the next successive relay is energized, and for a 4 microsecond pulse only the last relay is energized. Attention is also directed to the fact that the gate generated by multivibrator I04, for instance, which results in the operation of the second relay is the very same gate which preventsthe first relay-1 22 ;f rorn opera-ting; This isa very desirableinterlocking featurein that anypulse whichislong enoughtocause the-amplifier 91, for instance, to conduct;

will not only-cause the, second relay' tooperate but will also in fact prevent the first relay; I22- from operating; VVhether-or not thesecond relaywilloperate-will, of course, also'dependuponi whether the pulseis-long enoughto cause operation of the third successive multivibrator (not shown in, Fig. 4).

As'pointed out above, some of the duplicated;

tubes andtheir associatedcircuits and devices; have not been specifically illustrated, and it should be understood that they: are the same; as those shown except for certain adjustments necessary to, makethem function properly-inresponse to pulses of specific durations; For in;- stance; as illustrated; in Fig. 5, successive. multi j vibrators deliver-pulses or gates which are suc-v cessively longer; and successive critically adjusted amplifiers respond only to successively higher; grid voltages. Also, while the term saw-tooth wave has been used in. this specification as. referring to the initial substantially linear portijQ i v ofan exponential wave; it is to be understood that the disclosed circuits will operate equally" Well with true saw-toothwave inputs, and the circuits shown for producing exponential: out; puts may be replaced by circuits; for producing; true linear saw-tooth outputs;

Having. thus shown and described several specific arrangements; of circuits and devices em;- bodying; the; present invention, and having il;lus

'- trated graphically. how the system of Fig. 4 func-.

tions when. it isextended; to. four relays, it should of course be; understood that the particular sys tems' illustrated and operationally diagrammeddo not exhaust all the possible forms the inven; tion may take, and: that various changes, modifications and additions may be made to adapt the. invention to the particular problems encountered in practicing the same without departing; from; the spirit or scope; of the invention, which is defined in the following claims.

What is claimed is 1., In apparatus; of the; class described the. Com-- bination of a linear pulse integrator for: converting pulses of different durations into corresponding pulsesv whose amplitudes are a measure of said durations, a cooperating amplitude dis criminator connected to said integrator and responsive to said corresponding pulses whose amplitudes are greater than a first predetermined value, and an output control connected to said integrator and to the input of said discriminator to render said discriminator nonresponsive topulses whose amplitudes exceed a predetermined value greater than said first predetermined value.

2. In apparatus of the class described the com-. bination of a linear pulse integrator for converting pulses of different durations into corresponding pulses whose amplitudes are a, measure of said durations and a plurality of cooperating amplitude discriminators connected in parallel to the output of said integrator and responsive to said corresponding pulses, each successive amplitude discriminator being responsive only to pulses of greater amplitude than that to which the next preceding amplitude discriminator is responsive and each successive amplitude d is. criminator including a control for disabling each p c d mpl t d disc mi ator i qm produ n an ou put esp nd ng to ts input pulse sponding saw-tooth pulses Whose amplitudes are a measure of said durations and a plurality of cooperating amplitude discriminators connected in parallel to the output of said integrator and responsive to said corresponding pulses, each successive amplitude discriminator being responsive only to a pulse of greater amplitude than that to which the next preceding amplitude discriminator is responsive and each successive amplitude discriminator including an output control for disabling the preceding amplitude discriminator from producing an output corresponding to its input pulse on receipt of a pulse to which the respective successive amplitude discriminator is responsive, whereby only one amplitude discriminator will become effective when a single pulse is simultaneously applied to said plurality of amplitude discriminators in parallel.

4. In apparatus of the class described the combination of a linear pulse integrator for converting input pulses of different durations into saw-tooth pulses of peak amplitudes commensurate with said durations, a plurality of cooperating electron tubes having their inputs connected in parallel to the output of said integrator, each of said plurality of electron tubes being so biased that it will conduct only for that portion of a saw-tooth pulse applied to its input which exceeds a predetermined amplitude, and an output control for and connected to each electron tube and responsive to the next successive output control to render the output control of said tube non-responsive to inputs caused by saw-tooth pulses whose amplitudes exceed a predetermined value greater than the predetermined value for which said tube is biased to conduct.

5. In. apparatus of the class described the combination of a linear pulse integrator for converting pulses of different durations into corresponding pulses whose amplitudes are a measure of said durations, a plurality of cooperating amplitude discriminators, each connected in parallel to the output of said integrator and responsive to said corresponding pulses, each successive amplitude discriminator being responsive only to a pulse Of greater amplitude than that to which the next preceding amplitude discriminator is responsive, and an output control for and connected to each discriminator and responsive to the next successive output control to render the output control of said discriminator non-responsive to inputs caused by pulses whose amplitudes exceed a predetermined value greater than that to which said discriminator is responsive. V

6. In apparatus of the class described the combination of a linear pulse integrator for converting pulses of different durations into corresponding pulses Whose amplitudes are a measure of said durations, a series of amplitude discriminators, each connected in parallel to the output of said integrator and responsive to said corresponding pulses, each successive amplitude discriminator being responsive only to a pulse of greater amplitude than that to which the next preceding amplitude discriminator is responsive, and an output control for and connected to each discriminator, each output control in part including the next succeeding output control of the series, to render the output control of said discriminator non-responsive to inputs caused by pulses whose amplitudes exceed a predetermined value greater'than that to which said discriminator is responsive.

7. In apparatus of the class described the combination of a linear pulse integrator for converting input pulses of different durations into saw-tooth pulses having peak amplitudes of commensurate magnitude, a series of electron tubes having their inputs connected in parallel to the output of said integrator, each successive one of Said series of electron tubes being biased to a greater extent than the next preceding tube so that when suitable supply potentials are applied thereto each succeeding tube will start conducting at a predetermined amplitude of a saw-tooth pulse applied to its input, which amplitude for each succeeding tube is greater than for any preceding tube, a plurality of multivibrators, one for and connected to each electron tube and each successive multivibrator producing a successively longer negative output with each negative output having at least a portion occurring simultaneously with the trailing edge of the negative output of the next preceding multivibrator, and a corresponding plurality of amplifiers and differentiating circuits, the input of each amplifier being connected through the corresponding difierentiating circuit to its corresponding multivibrator and each multivibrator after the first of said series being electrically connected to the amplifier of the next preceding multivibrator, each amplifier being responsive to the differentiatedpulse produced simultaneously with the trailing edge of the negative output of its corresponding multivibrator, and wherein the negative output if any of each of said multivibrators after the first is of sufiicient magnitude to render ineffective the diiferentiated pulse of the preceding multivibrator, whereby only one of said amplifiers provides an output for an input pulse of specific duration.

8. In apparatus of the class described the combination of a linear pulse integrator for converting input pulses of difierent durations into sawtooth pulses having .peak amplitudes of commensurate magnitude, a series of electron tubes having their inputs connected in parallel to the output of said integrator, each successive on of said series of electron tubes being biased to a greater extent than the next preceding tube so that when suitable supply potentials are applied thereto each succeeding tube will start conducting at a predetermined amplitude of a saw-tooth pulse applied to its input, which amplitude for each succeeding tube is greater than for any preceding tube, a plurality of multivibrators, one for and connected to each electron tube and each successive multivibrator producing a successively longer negative output with each negative output having at least a portion occurring simultaneously with the trailing edge of the negative output of the next preceding multivibrator, and a plurality of amplifiers and differentiating circuits, one of each for each successive pair of said multivibrators, each amplifier being connected through the corresponding differentiating circuit to the first of its associated multivibrators and directly to the second of its associated multivibrators and responsive to the difierentiated pulse produced simultaneously with the trailing edge of the negative output of the first of its associated multivibrators, and wherein the negative output if any of each of said multivibrators after the first is of sufiicient magnitude to render ineffective the differentiated pulse of the preceding multivibrator, whereby only one of said plurality of am- :plifiers provides an output for an input pulse of specific duration,

9. In apparatus of the class described the combination of a series generators for electrically creating pulses of energy, a corresponding plurality of amplifiers each for and electrically connected to its respective generator, and an output control for each generator but the first and each connected between its respective generator and the amplifier of the next preceding generator for disabling that amplifier from producing an output corresponding to its input pulse when the successive generator creates a pulse of energy, whereby only one of said amplifiers can produce an output at any given 10. In apparatus of the class described the combination of a series of multivibrators and a plurality of controlled input amplifiers and differentiating circuits for and electrically connected to said multivibrators, each controlled input amplifier having its input connected through a diiferentiating circuit to the output of one multivibrator and directly to the similar output of the next successive multivibrator and responsive to the differentiated pulse produced simultaneously with the trailing edge of the output of said one multivibrator, and wherein at least a portion of said similar output if any of said next successive multivibrator occurs simultaneously with the trailing edge of the output of said one multivibrator and is of sufiicient magnitude to render ineifective the otherwise effective differentiated output of said one multivibrator, whereby only one of said amplifiers can produce an output at any given time.

11. In apparatus of the class described the combination of an integrator for converting input pulses of different durations into saw-tooth pulses whose peak amplitudes are of commensurate magnitude, a phase inverter to whose input is connected the output of said integrator, a first and second multivibrator connected to the first and second outputs respectivel of said phase inverter, said first multivibrator being adjusted to produce an output therefrom onl in response to an output from said phase inverter produced by an input to the apparatus whose duration exceeds a first given magnitude and said second multivibrator being adjusted to produce an output therefrom only in response to an output from said phase inverter produced by an input pulse to the apparatus whose duration exceeds a second given magnitude greater than said first magnitude, a difierentiating circuit, and an output circuit, the output of said first multivibrator being connected to the input of said output circuit through said difierentiating circuit to provide an output therefrom in response to an input pulse to said apparatus whose duration exceeds said first given magnitude, and the output of said second multivibrator being connected directly to the input of said output circuit and being of sufilcient magnitude to render ineffective the differentiated output of said first multivibrator if the duration of the input pulse to said apparatus exceeds said second magnitude.

12. In apparatus of the class described the combination of an integrating electron tube for converting input pulses of different durations into saw-tooth pulses whose peak amplitudes are of 1s commensurate magnitude, a cathode follower whose input is connected to the output of said input tube, a plurality of critically adjusted amplifiers connected in parallel to said cathode follower, each of said critically adjusted amplifiers being so biased that it will conduct only for that portion of a saw-tooth pulse applied to it which exceeds a predetermined amplitude and each of said amplifiers being diiierently biased, a corresponding plurality of multivibrators, each connected to its corresponding critically adjusted amplifier, a plurality of controlled input amplifiers and differen ug circuits, one of each for each successive A lr of said multivibrators, each controlled connected input amplifier being through its diff 'entiating circuit to the output of the first of s associated multivibrators and directly to the output of the next successive multivibrator, and a pluralit of isolating diodes, D. C. amplifiers, gas-type tubes, and relays, one of each for each controlled input amplifier, the output of each controlled input amplifier being applied to a separate isolating diode, the output of each diode being connected to a D. C. amplifier, the output of each D. C. amplifier being connected to a gas-type tube, and each gas-type tube including in its output circuit a relay, whereby only one of said plurality of relays is actuated in response to an input pulse of specific duration.

13. In apparatus of the class described the combination of an integrating electron tube for converting input pulses of different durations into saw-tooth pulses whose peak amplitudes are of commensurate magnitude, a cathode follower whose input is connected to the output of said input tube, a plurality of critically adjusted amplifiers connected in parallel said cathode follower, each of said critically adjusted amplifiers being so biased that it will conduct only for that portion of a saw-tooth pulse applied to it which exceeds a predetermined amplitude and each of said amplifiers being differently biased, a plurality of multivibrators, each connected to its corresponding critically adjusted amplifier, a plurality of gated amplifiers and differentiating circuits, one of each for each successive pair of said multivibrators, each gated amplifier including a screen grid and a control grid, the control grid of each gated amplifier being connected through its differentiating circuit to the output of the first of its associated multivibrators and the screen grid of each gated amplifier being directly connected to the output of its second associated multivibrator, and a plurality of additional multivibrators, power amplifiers, rectifiers, and relays, one of each for each gated amplifier, the output of each gated amplifier being applied to a separate one of said additional multivibrators, the output of each additional multivibrator vbeing connected to the corresponding power amplifier, the output of each power amplifier being connected to its corresponding rectifier, and each of said rectifiers being connected to its corresponding relay, whereby only one of said plurality of relays is actuated by an input pulse of specific duration.

14.111 a paratus of the class described the combination of an integrator for converting input pulses of different durations into saw-tooth pulses having peak amplitudes of commensurate magnitude, a series of electron tubes having their inputs connected in parallel to said integrator, each of said electron tubes being so biased that it will conduct only for that portion of a sawtooth pulse applied to its input which exceeds a predetermined value and each of said electron tubes being differently biased, a corresponding plurality of multivibrators, each connected to the output of its corresponding electron tube, and a plurality of amplifiers and diiierentiating circuits, one of each for each successive pair of said multivibrators, the input of each amplifier being connected through the corresponding differentiating circuit to the output of its corresponding multivibrator and directly to the output of another succeeding multivibrator, whereby only one of said plurality of amplifiers provides an output for an input pulse of specific duration.

15. In apparatus of the class described the combination of an integrator for converting input pulses of different durations into saw-tooth pulses having peak amplitudes of commensurate magnitude, a series of electron tubes having their inputs connected in parallel to said integrator, each of said electron tubes being so biased that it will conduct only for that portion of a saw-tooth pulse applied to its input which exceeds a predetermined value and each of said electron tubes being difierently biased, a corresponding plurality of multivibrators, each connected to the output of its corresponding electron tube, and a plurality of output circuits, one for and connected to each pair of said multivibrators and responsive to the output of the second of its associated multivibrators to render ineiiective any simultaneous output of the first of its associated multivibrators, whereby an output is produced from a different one of each of said output circuits in response to input pulses of respectively different specific durations.

16. In apparatus of the class described the combination of an integrator for converting pulses of different durations into corresponding pulses whose amplitudes are a measure of said durations and a plurality of cooperating amplitude discriminators connected in parallel to the output of said integrator and responsive to said correspending pulses, each successive amplitude dis-- criminator being responsive only to pulses of greater amplitude than that to which the next preceding amplitude discriminator is responsive, each amplitude discriminator but the last including in circuit therewith a delay circuit timed to delay its output a time at least equal to the time at which the next amplitude discriminator would be rendered responsive if the input pulse were of sumcient duration, and each successive amplitude discriminator including a control for disabling each preceding amplitude discriminator on receipt of a pulse to which it is responsive, whereby only one amplitude discriminator will produce an output for a single pulse applied simultaneously to said plurality of amplitude discriminators in parallel.

17. In apparatus of the class described the combination of an integrator for converting pulses of different durations into corresponding saw-tooth pulses whose amplitudes are a measure of said durations and a plurality of cooperating amplitude discriminators connected in parallel to the output of said integrator and responsive to said corresponding pulses, each successive amplitude discriminator being responsive only to a pulse of greater amplitude than that to which the next preceding amplitude discriminator is responsive, each amplitude discriminator but the last including in circuit therewith a delay circuit timed to delay its output a time at least equal to the time at which the next amplitude discriminator would be rendered responsive if the input pulse were of sufiicient duration, and each successive amplitude discriminator including an output control for disabling the preceding amplitude discriminator on receipt of a pulse to which it is responsive, whereby only one amplitude discriminator willbecome effective when a single pulse is simultaneously applied to said plurality of amplitude discriminators in parallel.

18. In apparatus of the class described the combination of a linear pulse integrator for converting input pulses of different durations into sawtooth pulses of peak amplitude commensurate with said durations, a series of electron tubes having their inputs connected in parallel to the output of said integrator, each successive one of said series of electron tubes being biased to a greater extent than the next preceding tube so that when suitable supply potentials are applied thereto each succeeding tube will start conducting at a predetermined amplitude of a saw-tooth pulse applied to its input, which amplitude for each succeeding tube is greater than that for any preceding tube, a corresponding pluralit of amplifiers and control circuits, each amplifier being connected through the corresponding control circuit to its corresponding electron tube and also connected to and responsive to the output of the control circuit, of the next successive electron tube to render ineffective any simultaneous output of its own control circuit, and each control circuit including in circuit therewith a delay circuit timed to introduce a time delay at least equal to the additional time required for the next successive biased electron tube to start conducting due to the same input pulse if said input pulse is of sufiicient duration, whereby only one amplifier will become effective when a single saw-tooth pulse is simultaneously applied to the inputs of said electron tubes.

LIONEL I-I. ORPIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,158,285 Koch May 16, 1939 2,275,930 Torcheux Mar. 10, 1942 2,281,934 Geiger May 5, 1942 2,282,046 Goldsmith May 5, 1942 2,340,213 Ellsworth Jan. 25, 1944 2,359,447 Seeley Oct. 3, 1944 2,392,546 Petersen Jan. 8, 1946 2,399,668 Francis May 7, 1946 2,413,440 Farrington Dec. 31, 1946 2,419,548 Greig Apr. 29, 1947 2,425,066 Labin Aug. 5, 1947 2,425,314 Hansell Aug. 12, 1947 2,425,316 Dow Aug. 12, 1947 2,453,454 Norwine Nov. 9, 1948 

